Sunday 14 August 2016 23.21 EDT
First published on Sunday 14 August 2016 05.24 EDT

More than 10,000 people are in shelters and more than 20,000 people have been rescued across south Louisiana amid widespread flooding, Governor John Bel Edwards has said.

Baton Rouge river center, a major events location, would be opened on Sunday to help care for the large numbers of evacuees, he said, as the federal government declared a major disaster in four parishes.

Edwards said Barack Obama called him and said “the people of south Louisiana are in his thoughts and prayers and the federal government will be a solid partner”.

Edwards emphasized Sunday that the rain-caused flooding was “not over”.

He said the fatalities have not risen from the three dead reported on Saturday. One person is unaccounted for in St Helena Parish. Edwards added that the storm has “subsided in its intensity” but encouraged people to not go out and “sightsee” even as the weather improves.

The governor says water is continuing to rise in some areas even though the sunshine is out.

Emergency crews plucked motorists from cars stranded by high water along a seven-mile stretch of highway in southern Louisiana and pulled others from inundated homes and waist-deep waters.

Edwards declared a state of emergency over the weekend, calling the floods unprecedented and “historic”. He and his family were forced to leave the governor’s mansion when chest-high water filled the basement and electricity was turned off.

“That’s never happened before,” said the governor, whose family relocated to a state police facility in the Baton Rouge area.

The governor toured flood-ravaged areas by helicopter on Saturday after rivers and creeks burst their banks. One of the worries, he said, is that as the rain lessens in the next several hours, people will become complacent and feel too at ease in areas where waters may still be rising for several days, getting in cars in areas that could still be dangerous.

“I’m still asking people to be patient. Don’t get out and sightsee,” Edwards said. “Even when the weather is better, it’s not safe.”

In one rescue on Saturday, two men on a boat pulled a woman from a car that was almost completely underwater. The woman, who was not initially visible in a video of the rescue, yelled from inside the car: “Oh my God, I’m drowning.”

One of the rescuers, David Phung, jumped into the brown water and pulled the woman to safety. She pleaded with Phung to get her dog, but he could not find it. After several seconds, Phung took a deep breath, went underwater and resurfaced – with the small dog. Both the woman and the dog appeared OK.

Elsewhere, rescues continued late on Saturday, including missions by crews in high-water vehicles who pulled motorists from one swamped stretch of Interstate 12 between Baton Rouge and nearby Tangipahoa Parish. Major Doug Cain, spokesman of the Louisiana state police, said about 125 vehicles became stranded on the seven-mile stretch.

Residents use a raft to evacuate homes in Baton Rouge. Photograph: John Oubre/AP

In the Livingston Parish city of Denham Springs, a suburb of Baton Rouge, entire shopping centers were inundated, with only roofs of cars peeking above the water. In many places, the water was still rising.

In Baker, just north of Baton Rouge, residents were rescued by boats or waded through waist-deep water to reach dry ground. Dozens awoke on Saturday morning at a makeshift Red Cross shelter only a few blocks from their flooded homes and cars.

Shanita Angrum, 32, said she called 911 on Friday morning when she realised flood waters had trapped her family in their home. A police officer carried her six-year-old daughter, Khoie, on his back while she and her husband waded behind them.

“Snakes were everywhere,” she said. “The whole time I was just praying for God to make sure me and my family were OK.”

Beginning on Friday, six to 10 inches (15-25cm) of rain fell on parts of Louisiana and several more inches of rain fell on Saturday, according to the National Weather Service. Some areas got even more rain. In a 24-hour period, Baton Rouge had as much as 11 inches while one weather observer reported more than 17 inches in Livingston.

Forecasters expected a turn to the north by the system on system, warning portions of central and northern Louisiana could see heavy rain into next week.

Mississippi’s governor, Phil Bryant, declared a state of emergency for several counties in his state as it also battled the heavy rainfall.